FR2891605A1 - Load control structure for work vehicle e.g. tractor, has control device controlling pump swash plate such that operating position of continuously variable speed change device moves to limit operating position - Google Patents

Abstract

The structure has a control device (31) calculating a drop amount of an actual engine rotation speed from a set rotation speed, and setting a limit operation position for a continuously variable speed change device. The control device controls a pump swash plate (31A) such that an operating position of the continuously variable speed change device moves to the limit operating position based on the set limit operating position and information from a swash plate sensor (30), where the control device includes a command unit for commanding a change of correlation data. An independent claim is also included for a method for controlling a speed of a work vehicle.

Description

2891605 1

  The present invention relates to a load control structure and the associated control method for heavy duty vehicles.

  Such a vehicle conventionally possesses, among other things, a fixed rotational speed detecting means for determining a fixed rotational speed for the vehicle engine for heavy work; means for detecting the actual rotational speed, which measures the actual rotational speed of the motor; a continuously variable gearshift device which receives power from the heavy-duty vehicle engine; velocity shift position detecting means for determining the shifting actuation position of the continuously variable shifting device; an actuating means for changing gears in the continuously variable speed changing device; control means for controlling the operation of the actuating means.

  In the above-mentioned load control mechanism, the control means controls the actuating means to control the continuously variable speed changing device based on the amount of lowering rotational speed of the motor relative to at the rotation speed set so as to cause the continuously variable speed changing device to a speed position which is a function of the amount of lowering. (See, for example, JP 2002-22006.) In the above structure, the continuously variable speed shifter is simply brought to a speed position in accordance with the amount of lowering relative to the set rotational speed of the shifter. engine. It is therefore difficult to obtain a satisfactory charge control which is appropriate for different engine loads, which differ according to the operating conditions.

  An object of the invention is to provide an advantageous charge control for different loads of the engine, which charges differ depending on the operating conditions.

  Accordingly, a load control structure for heavy duty vehicles according to one aspect of the invention comprises: fixed rotational speed detecting means for determining the fixed rotation speed of the heavy duty vehicle engine; an actual rotational speed detecting means which detects the actual motor rotation speed; a continuously variable gearshift device which receives power from the heavy-duty vehicle engine; velocity shift position detecting means for determining the shift operating position of the continuously variable velocity shifter; an actuating means for shifting the continuously variable speed changing device; control means for controlling the operation of the actuating means; wherein the control means calculates the amount of lowering of the actual rotational speed of the motor relative to the rotational speed set based on the information detected from the fixed rotational speed detecting means and the control means. sensing the actual rotational speed, and setting a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with operating positions of the continuously variable speed changing device, and controls the actuating means so that the operating position of the continuously variable speed changing device moves to the limit actuating position on the base the fixed limit actuation position and the information detected by the change position detecting means and wherein the control means has instruction grant means for providing a change instruction of the correlation data.

  A control structure according to another aspect of the invention comprises: fixed rotational speed detecting means for detecting the rotational speed set for the engine of a heavy-duty vehicle; means for detecting the actual rotational speed, which detects the actual rotational speed of the motor; a continuously variable gearshift device which receives power from the heavy-duty vehicle engine; shift position detecting means for determining the shift actuation position of the continuously variable shift device; an actuating means for shifting the velocities of the continuously variable speed changing device; control means for controlling the operation of the actuating means; and an operating speed setting means for setting an operating speed at which the continuously variable speed changing device is actuated; wherein the control means calculates the magnitude of lowering the actual rotational speed of the motor relative to the rotational speed set based on the information detected from the fixed rotational speed detecting means and the sensing means of At the actual rotational speed, the control means sets a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with operating positions of the continuously variable speed changing device, the control means controls the actuating means so that the operating position of the continuously variable speed changing device moves to the limit actuating position on the base of the fixed limit actuation position and information detected from the detection means shifting position, and wherein the control means controls the operation of the actuating means so that the continuously variable shifter is actuated by the actuating means at the operating speed set by the shifting means. operating speed setting.

  The invention also relates to a method for controlling the speed of a vehicle intended for heavy work, the vehicle intended for large jobs having: a fixed speed detection means for detecting the rotational speed set for the engine of a vehicle for heavy work; means for detecting the actual rotational speed, which detects the actual rotational speed of the motor; a continuously variable speed changing device (10) which receives power from the heavy duty vehicle engine; shift position detecting means for determining the shift actuation position of the continuously variable shift device; an actuating means for shifting the velocities of the continuously variable speed changing device; and control means for controlling the operation of the actuating means; the method comprising the steps of: calculating the amount of lowering of the actual rotational speed of the motor relative to the rotational speed set based on the information detected from the fixed rotation speed detection means and the real rotation speed detection means; setting a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with the operating positions of the changeover device continuously variable speed; controlling the actuating means so that the operating position of the continuously variable speed changing device moves to the limit actuating position on the basis of the fixed limit actuating position and information detected from the shift position detecting means; and change the correlation data.

  According to another aspect of the invention, the subject of the invention is a method for controlling the speed of a vehicle intended for heavy work, this vehicle having: a means for detecting the fixed speed of rotation making it possible to detect the speed of rotation set for the engine of a heavy-duty vehicle; means for detecting the actual rotational speed, which detects the actual rotational speed of the motor; a continuously variable gearshift device which receives power from the heavy-duty vehicle engine; shift position detecting means for determining the shift actuation position of the continuously variable shift device; an actuating means for shifting the velocities of the continuously variable speed changing device; control means for controlling the operation of the actuating means; an operating speed setting means for setting an operating speed at which the continuously variable speed changing device is actuated, the method being characterized in that the method comprises the following operations: calculating the lowering amount of the actual rotational speed of the motor with respect to the rotational speed set based on the information detected from the fixed rotational speed detection means and the actual rotational speed detecting means; setting a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with the operating positions of the changeover device continuously variable speed; controlling the actuating means so that the actuating position of the continuously variable speed changing device moves to the limit actuating position on the basis of the fixed limit actuating position and sensing information detected at from the shift position detecting means; and controlling the operation of the actuating means such that the continuously variable speed changing device is actuated by the actuating means at the actuating speed set by the actuating speed setting means.

  The following description, designed as an illustration of the invention, is intended to provide a better understanding of its features and advantages; it is based on the accompanying drawings, among which: Figure 1 is a side view of a tractor, shown as an example of a vehicle for heavy work; Figure 2 is a schematic diagram showing the tractor drive train; Figure 3 is a sectional side view showing a portion of the tractor drive train; Figure 4 is a sectional plan view showing a portion of the tractor drive train; Fig. 5 is a diagram showing the hydraulic circuit; Fig. 6 is a block diagram showing the control structure; Fig. 7 is a graph showing the correlation between the activated positions of the shift pedal and the activated positions of the pump swashplate; Figure 8 is a graph showing the correlation between the deviations and target operating speeds of the swash plate and the target operating speeds; Figs. 9A, 9B and 9C are graphs showing the correlation that exists between the swashplate positions and the rotational speeds of the motor; Fig. 10 is a graph showing the movement of the pump swash plate as the position of the motor swash plate is changing; Fig. 11 shows how the position of the pump swash plate 35 is displayed on a liquid crystal display device; Fig. 12 is a sectional plan view showing a mechanical servo control mechanism; Fig. 13 is a hydraulic circuit diagram showing the mechanical servo control mechanism and the switching mechanism; Fig. 14 is a hydraulic circuit diagram showing an arrangement in which only an electronic servocontrol mechanism is used; Fig. 15 is a hydraulic circuit diagram showing an arrangement in which only a mechanical servocontrol mechanism is used.

  The entire side view of a tractor taken as an example of a heavy duty vehicle is shown in Figure 1. This tractor has a front frame 2 which supports the engine 1 via a means that isolates vibrations, front wheels 3 mounted on either side of the front frame 2, a gear case 4 which also functions as a chassis connected to the engine 1, and rear wheels 5 placed on either side of the gear case 4 The heavy duty vehicle has a driver portion 8 equipped with a steering wheel 6, a driver seat 7, etc., above the gear case 4. The tractor has a plurality of sensors which are described herein. -Dessous. These sensors are well known and conventional, such as rotation detectors, which may be optical or magnetic, or of another type, and will therefore not be described in detail below.

  As represented in FIGS. 2 to 4, the power coming from the engine 1 is transmitted to the continuously variable hydrostatic gear changing device (which constitutes an example of a continuously variable gearshift device) 10, which acts as an apparatus main gearshift via a main clutch 9 of the dry clutch type, etc. The driving power from the continuously variable hydrostatic gear changing device 10 is transmitted to the right and left front wheels 3 and to the right and left rear wheels 5 via the stepped gear shifter (which is a example of a multi-speed shifter) 11, which functions as an auxiliary shifting device, which can be moved in three speed positions, the high speed position, the medium speed position and the low speed position , the differential gear 12 of the front wheels, or the differential gear 13 of the rear wheels. The high operating power on the continuously variable hydrostatic type gear change device 10 is transmitted to the power take-up shaft 15 via the hydraulically operated clutch 14, etc. The gear case 4 is formed by the connection of the four housing parts: the first housing part 4A which houses the main clutch 9, etc., the second housing part 4B, which houses the gear shifting device 10 continuously variable of the hydrostatic type, etc., the third housing portion 4C housing the hydraulic operating clutch 14, etc., and the fourth housing portion 4D which houses the stepped type gear changing device 11, etc. As shown in FIGS. 2 to 5, the continuously variable speed changing device 10 of the hydrostatic type has an axial plunger type variable displacement pump 16, an axial plunger type variable displacement motor 17, etc., which are housed in the second housing portion 4B, where the power from the variable displacement pump 16, the speed of which is not changed, is delivered as power for an operation, while the power whose speed is is changed, which comes from the variable displacement motor 17, is issued as power for displacement. The charge oil from a charge pump 21 driven by the power of the engine is supplied to a closed circuit 20 via a charge oil path 22, a check valve 23, etc., which is formed by connection of the variable displacement pump 16 and the variable displacement motor 17 by means of the first oil path 18 and the second oil path 19.

  As can be seen in FIGS. 1 and 4 to 6, this tractor is equipped, in its cockpit 8, with a servo control mechanism 25 with which the swash plate (to which reference will be made hereinafter below). 16A of the variable displacement pump 16 is actuated, based on the actuation of the shift pedal (which is an example of a shift actuating element). that one pushes towards its neutral position.

  As can be seen in FIGS. 4 to 6, the servo control mechanism 25 has a hydraulic pump cylinder 26 for continuously operating the pump swash plate 16A (an example of an actuating means), a valve 27, which regulates the flow of hydraulic fluid to the cylinder 2891605 hydraulic pump 26, a control valve 28 which maintains a predetermined value the hydraulic pressure applied to the servo valve 27, a pedal sensor (example actuating position detecting means) 29 having a potentiometer for detecting the activated position of the shift pedal 24, and a swash plate sensor (an example of a shift position detecting means) ) Which has a potentiometer detecting the actuating position of the pump swash plate 16A from the actuation variable of the pump cylinder 26, and a control device (an example of control means) 31 which has a microcomputer to which information detected by the sensors is inputted, for example the pedal sensor 29, the swash plate sensor 30, etc. The pump cylinder 26 is housed in the second housing portion 4B with a forward travel deceleration spring 32 and a rearward travel deceleration spring 33 which urges the swash plate 16A toward its neutral position. When hydraulic fluid is supplied to the hydraulic chamber 34 for forward shifting, the pump swashplate 16A is actuated in the direction of increasing velocity (or acceleration) of movement toward the front against the thrust force of the spring 32 to decelerate the forward movement. When hydraulic fluid is supplied to the hydraulic chamber 35 for rearward displacement speed change, the pump swashplate 16A is actuated in the upshift direction of the rearward movement against the spring force 33 deceleration of displacement.

  The servo valve 27 has an electromagnetic proportional valve 36 for forward movement for controlling the flow of hydraulic fluid to the hydraulic chamber 34 for the forward displacement of the pump cylinder 26 and an electromagnetic proportional valve. 37 for the rearward movement, which controls the flow of hydraulic fluid to the hydraulic chamber 35 for the speed variation of the displacement towards the rear of the pump cylinder 26. The regulating valve 28 distributes the hydraulic fluid sent since the power steering power steering pump 38 for operating the clutch 14 and a hydraulic power steering device 39 with a pressure which is adapted to each operation.

  The feed oil path 41 to the servo valve 27 is connected to the pressure port 28A of the regulating valve 28 to which the feed oil path 40 for actuating the pressure regulator 28 is connected. clutch 14.

  The controller 31 has at least one microprocessor, a memory and the remainder of the known hardware that is necessary to provide a communication function, as well as other functions and algorithms described later. As shown in FIG. 6, the controller 31 has matching data (an example of correlation data) which correlates the activated position (or actuation position) of the shift pedal 24 with the the operating position of the pump swash plate 16A, and a pump swash plate control means 31A which has a control program which operates the pump swashplate 16A controlling the operation of the proportional valve 36 of movement towards the pump. forward or backward movement proportional valve 37 on the basis of the mapping data and detected information or signals from the pedal sensor 29, sensed information from the swash plate sensor 30, etc. The pump swash plate control means 31A matching data establishes the match between the activated position of the shifter pedal 24 and the operating position of the pump swash plate 16A so that the larger the quantity is important. actuating relative to the neutral position of the shift pedal 24 in the forward speed increase direction, and the greater the amount of actuation relative to the neutral position of the swash plate of pump 16A in the direction of increasing speed of the forward movement and so that the greater is the amount of actuation relative to the neutral position of the shift pedal 24 in the direction of increase of the speed in the backward movement and more important is the amount of operation relative to the neutral position of the swashplate. mpe 16A in the direction of increasing speed of the backward motion (see Figure 7).

  The control program of the pump swash plate control means 31A sets the operating position of the pump swash plate 16A which corresponds to the activated position of the speed shift pedal 249 that the pedal sensor 29 has detected under the target operating position of the pump swashplate 16A on the basis of the stored matching data and the information detected from the pedal sensor 29.

  On the basis of the fixed target operating position and the information detected from the swash plate sensor 30, the operation of the proportional valve 36 relative to the forward movement and the proportional valve 37 relative to the displacement to the the rear so that the target actuating position of the pump swash plate 16A and the actual operating position are brought into coincidence. By this control operation, it is ensured that the vehicle can be moved forwards or backwards at a speed which is a function of the activated position of the shift pedal 24.

  Thus, the servo control mechanism is of the electronically controlled type, where the pump swing plate control means 31A controls the operation of the proportional valve 36 relative to the forward movement or the proportional valve 37 relative to the displacement. rearwardly to actuate the pump cylinder 26 to actuate the pump swash plate 16A of the continuously variable hydrostatic rate changing device 10 based on the information detected from the pedal sensor 29 and the detected information. from the swash plate sensor 30. The servo control mechanism 25 activates the pump cylinder 36 directly with the output pressure of the proportional valve 36 relative to the forward movement or the proportional valve 37 relative to the displacement to the the rear, which passes through the pressure port 28A of the regulating valve 28 (of direct action type).

  Stable controlled piloting pressure can be obtained and an actuation control of the pump cylinder 26 can be carried out with sufficient accuracy, as compared with the device in which the pump cylinder 26 is driven by means of the outlet pressure coming from the charge oil path 22 where the pressure changes due to the fluctuations of the pressure in the closed circuit 20 of the continuously variable hydrostatic type changeover device 10, or changes in the rotational speed of the engine. Therefore, the speed control of the vehicle which makes a forward or a rearward movement at a speed which is a function of the position of the gear shift pedal 24 with sufficient accuracy on the base of the information detected from the pedal sensor 29 and the information detected from the swash plate sensor 30 while using a direct acting slaved control mechanism 25, which is relatively inexpensive.

  The controller 31 has an actuation program which calculates the difference between the target actuation position of the pump swash plate 16A which is determined by the pump swash plate control means 31A and the actual actuation position. which is based on the target operating position of the pump swash plate 16 and the detected information from the swash plate sensor 30; a plurality of matching data (which is an example of correlation data) which correlates the deviation of the target operating position of the pump swashplate 16A with the actual operating position and the operating speed of the 16A pump swash plate; and the first actuating speed setting means 31B has a control program which sets the target operating speed of the pump swashplate 16A on the basis of these mapping data and the calculated result of the operating program .

  Each of the matching data of the first actuating speed setting means 31B correlates the difference of the pump swashplate 16A with the operating speed of the pump swashplate 16A (see Fig. 8) so that, when there is a large difference between the actual operating position of the pump swash plate 16A detected by the swash plate sensor 30 and the target operating position of the pump swash plate 16A determined by the tray control means 31A. oscillating pump, the operating speed of the pump swash plate 16A becomes larger and so that the operating speed of the pump swash plate 16A relative to a given offset of the pump swash plate 16A in the displacement in the opposite direction is less than the oscillating pump 16A oscillating actuating speed relative to a given offset of the pump swash plate 16A in a forward motion .

  The control program of the first operating speed setting means 31B is set so that the operating speed of the pump swashplate 16A corresponding to the offset of the calculated pump swash plate 16A is set in accordance with the speed 2891605 12 of the aiming of the pump swash plate 16A on the basis of the mapping data and the calculation result of the operating program. The target target actuation speed is outputted to the pump swash plate control means 31A.

  In the vehicle speed control, the control program of the pump swash plate control means 31A controls the operation of the proportional valve 36 relating to the forward movement or the proportional valve 34 relating to the rearward displacement so that the pump swash plate 16A is operated at the target operating speed which is fixed by the first operating speed setting means 31B. By this control operation, the rounding can be controlled while improving the response capacity of the pump swash plate 16A with respect to the actuation of the shift pedal 24. As a result, the vehicle can reaching the speed set by the actuated position of the shift pedal 24 quickly and accurately. Since the operating speed of the pump swash plate 16A in the rearward movement is lower than the operating speed of the pump swashplate 16A during a forward movement, the shifting operation of the shifting device Continuously variable hydrostatic type 10 in a rearward movement is effected more gradually compared to the speed change operation of the continuously variable hydrostatic speed change device 10 during a forward motion. , and it becomes easy to perform a speed change operation of the continuously variable hydrostatic shift gear device 10 during a backward motion when it is difficult to have a speed detection compared to the relative one. moving forward.

  The controller 31 has a data changing means 31C which is provided with the control program changing the mapping data used by the first operation speed setting means 31B. As described below, the data changing means 31C is set so that the matching data used by the first actuating speed setting means 31B varies appropriately in various situations.

  The data changing means 31C modifies the mapping data which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A based on the operating position of a dial. a regulator (an example of a user operated control means) 42 which has a potentiometer in the cockpit 8 so that when the control dial 42 is further actuated towards the fast side relative to the reference position , The operation of the pump swash plate 16A is carried out more rapidly by changing the matching so that the offset of the pump swash plate 16A corresponds to the operating speed of the pump swash plate 16A so that the operating speed of the pump swash plate 16A for a given offset of the pump swash plate 16A becomes faster. Further, when the regulating dial 42 is further actuated toward the slow side relative to the reference position, the operating speed of the pump swash plate 16A relative to the offset of the pump swash plate 16A is lower, if although the operation of the pump swash plate 16A is carried out more gradually.

  Thus, by operating the regulating dial 42, the response to a gear change operation of the continuously variable speed changing device of the hydrostatic type 10 can be modified by the gearshift pedal 24 as a function of the driver's desires. which brings improved speed change characteristics.

  The data changing means 31C modifies the mapping data on the basis of the information detected from the oil temperature sensor 43 by which the temperature of the hydraulic fluid supplied to the regulating valve 28 is detected, so that the The operating speed of the pump swashplate 16A is correlated with a given offset from the pump swash plate 16A so that the operating speed of the pump swashplate 16A relative to the offset of the pump swashplate 16A is gradually increased. as a function of the drop in the oil temperature, so that the lower the temperature of the hydraulic fluid, the more gradually the operation of the pump swash plate 16A.

  Thus, the system takes into account that the viscosity of the hydraulic fluid increases and that the response of the pump swash plate 16A softens with the drop in the temperature of the hydraulic fluid. The target operating speed of the pump swashplate 16A is set at a lower level for a lower temperature of the hydraulic fluid. This may help to prevent a rounding from this drop in the response of the pump swash plate 16A, which is more likely to occur when the temperature of the hydraulic fluid is not taken into account and when the fluid temperature hydraulic is low.

  The data changing means 31C modifies the mapping data which correlates the difference of the pump swashplate 16A with the operating speed of the pump swashplate 16A based on the detected information from the shifter sensor. speed (which is an example of transmission ratio determining means) 45, which has a potentiometer which detects the transmission ratio of the stepped type gear shifter 11 based on the operating position of the shift lever lower speed 44 of the driver's station 8, so that the higher the transmission ratio of the gear type gear shifter is, the greater the speed with which the operation of the pump swash plate 16A performs. Therefore, the means 31C modifies the correspondence that correlates the gap of the pump swashplate 16A with the operating speed of the pump swashplate 16A, so that the operating speed of the pump swashplate 16A returns to a The given offset of the pump swashplate 16A is greater in response to the increase in the transmission ratio of the shifter 11.

  Thus, the target operating speed of the pump swashplate 16A is set higher by the fact that the reaction response to the operation of the pump swashplate 16A becomes slower, since the transmission ratio of the swashplate Step type speed 11 is set on the higher speed side. Thus, regardless of the transmission ratio of the stepped type gear shifter 11, the response obtained during a gear shift operation of the continuously variable hydrostatic gear shifter by means of the shifting pedal 24 is consistent.

  The data changing means 31C modifies the correspondence to be used for the data which correlates the difference of the pump swashplate 16A with the operating speed of the pump swashplate 16A so that the lower the speed of rotation. Actuation of the speed shift pedal 24 and more will be effected by actuation of the pump swash plate 16A, based on information detected from the operating speed detection means 46, which means detects the speed of actuation of the shift pedal 24, so that, with a decrease in the speed of actuation of the shift pedal, the operating speed of the pump swash plate 16A for a given distance of the 16A pump swash plate will become more gradual. The speed of actuation of the gearshift pedal is obtained by deriving the output signal of the pedal sensor 29 with respect to time. Thus, the detection means 46 is considered to have the pedal sensor 29 and the control device 31.

  Therefore, even if the change pedal 24 is operated very slowly, the movement of the pump swash plate 16A is delayed with respect to the operation of the shift pedal 24. Thus, since the possibility that the If the pump swashplate 16A is operated following the actuation of the shift pedal 24, causing a jerk-like speed change, can be avoided, a smooth shifting operation of the device 10 can be performed. hydrostatically variable speed changeover by means of the shift pedal 24, independently of the speed of operation of the shift pedal 24.

  The means 46 for detecting the speed of actuation has the pedal sensor 29 and the actuation program, which the data transfer means 31C has, in order to calculate the speed of actuation of the gearshift pedal 24. based on the information detected from the pedal sensor 29.

  The data changing means 31C changes the mapping data to be used into the matching data which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A on the basis of information detected from the swash plate sensor 30, so that when it is detected that the operating position of the pump swash plate 16A is close to the neutral position, or dead point, or is at the In the neutral position, the actuation of the pump swash plate 16A is smooth, so that the operating speed of the pump swashplate 2891605 16 for a given offset of the pump swashplate 16A is limited to the reduced velocity side. .

  Therefore, when the pump swash plate 16A is placed in the vicinity of the neutral position or is in the neutral position, even if the shift pedal 24 is suddenly depressed, since the pump swash plate 16A is not operated quickly in the direction of speed increase with the current operation, the 16A pump swashplate will be gently operated in the direction of increasing speed. Thus, even if the current actuation of the shift pedal 24 is performed very quickly, a smooth start is ensured without any sudden start or sudden acceleration, from a very slow speed.

  The data changing means 31C changes the mapping data used which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A on the basis of the information detected from the rotation sensor ( which is an example of load sensing means) 47, which detects the rotational speed of the motor, and the target operating position of the pump swash plate 16A which is fixed by the pump swash plate control means 31A. so that when the target operating position of the pump swashplate 16A is set on the low speed side when the rotational speed of the motor is low, the operation of the pump swash plate 16A is detected quickly, so that that, in response to a drop in the rotational speed of the motor, the rotational speed of the pump swash plate 16A for a given gap of the pump swash plate 16A becomes superior. The mapping data is modified so that when it has been detected that the target operating position of the pump swashplate 16A is set on the high speed side while the rotational speed of the motor is being set. As a result, the operation of the pump swash plate 16A is performed smoothly so that the operating speed of the pump swashplate 16A for a given offset of the pump swash plate 16A slows in response to the rise of the pump swash plate 16A. motor rotation speed.

  If the shift pedal 24 is actuated to the deceleration side when the rotational speed of the motor is low due to an increase in the displacement load, or the like, the pump swash plate 16A is activated rapidly in the 2891605 17 deceleration direction in response to activation, which relieves the excessive load of the engine. This reduces the engine stall problem occurring despite the fact that the shift pedal 24 has been actuated in the deceleration direction because the reduction of the engine load is too slow due to the slow response of the engine. continuously variable speed changing device 10 of the hydrostatic type. When the shift pedal 24 is actuated on the acceleration side while the rotational speed of the motor increases due to a reduction in the displacement load, or the like, since the actuation in the direction of increase speed, the pump swash plate 16A on the basis of the actuation is carried out gently, the rapid increase in vehicle speed, which results from the rapid speed increase actuation of the 16A pump swash plate with the increase of the rotational speed of the motor, is avoided. Thus, the speed change operation of the continuously variable speed changing device 10 of the hydrostatic type, under the action of the shift pedal 24, can be effected satisfactorily regardless of the variation of the rotational speed. of the motor.

  The shift means 31C modifies the mapping data which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A based on the information detected from the brake sensor ( an example of the brake detecting means 49) having a potentiometer which detects the operation of the brake mechanism (not shown) from the operating position of the brake pedal 48 at the driver's station 8 so that, when the brake mechanism exerts the braking action, an actuation in the deceleration direction of the pump swash plate 16A is effected in such a manner that the speed of actuation of the pump swash plate 16A for a given offset of the pump swash plate 16A becomes larger, account being taken of the fall of the speed of the vehicle under the braking action of the mechanism of brake.

  This prevents interference between the continuously variable hydrostatic shift device 10 and the brake mechanism during the braking operation when the current operation of the shift pedal 24 ceases and the operation in progress. of the brake pedal 48 is executed. Thus, this helps to increase the useful life of the continuously variable hydrostatic shift gear device 10 as well as the brake mechanism.

  The data changing means 31C modifies the mapping data which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A on the basis of the information detected from the sensor. vehicle speed (speed detection means) 50, which determines the speed of the vehicle from the output rotational speed of the stepped gear type 11, so that when the vehicle speed is low, the operating speed of the pump swash plate 16A for a given offset of the pump swash plate 16A is slow, so that the operation of the pump swashplate 16A is gradual in response to the falling of the velocity of the vehicle.

  When traveling at a reduced speed, the response of the pump swash plate 16A to an actuation of the shift pedal 24 becomes less sensitive, which makes it easier to perform a step-by-step operation. vehicle needed at low speed.

  The data changing means 31C changes the mapping data which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A based on the information detected from the sensor 30. of swing plate, and the target actuation position of the pump swash plate 16A fixed by the pump swash plate control means 31A, so that when the target operating position of the pump swash plate 16A is fixed on the speed increasing side with respect to the actual operating position, the operation of the pump swash plate 16A is performed more smoothly and so that when the target operating position of the pump swash plate 16A is set on the slowing side with respect to the actual operating position, the operation of the pump swash plate 16A is effected promptly, and so that when the neutral position Being between the target operating position of the pump swash plate 16A and the actual operating position, the operation of the pump swash plate 16A is much faster.

  Therefore, depending on the relationship that exists between the target operating position of the pump swash plate 16A and the actual operating position 2891605, the operating speed of the pump swashplate 16A for a given gap of the plateau Oscillating pump 16A varies.

  The responses to the speed increase operation and the speed-slowdown operation of the continuously variable hydrostatic speed change device 10 by the shift pedal 24 can be made different by this method. Since the increase of the engine load via the speed increase operation of the continuously variable speed changing device 10 of the hydrostatic type is reduced and the engine load is made via the slowing down operation of the engine changeover device. If the hydrostatic-type continuously variable speed is reduced, an engine stall caused by a continuously variable speed hydrostatic gear changing device 10 shifting operation via the shift pedal 24 during a heavy load can be effectively prevented. . Since the operating delay of the pump swash plate 16A in response to operation of the shifting pedal 24 is prevented, the shifting operation of the continuously variable hydrostatic shift gear device 10 in the direction front or rear direction by the shift pedal 24 can be performed under comfortable conditions.

  The shift means 31C changes the mapping data which correlates the difference of the pump swash plate 16A with the operating speed of the pump swashplate 16A based on the information detected from the swash plate sensor. 30, and the target actuation position of the pump swash plate 16A fixed by the pump swash plate control means 31A so that at the beginning of the vehicle movement, where the pump swash plate 16A is actuated in the direction of increasing the speed from the neutral position, the actuation of the pump swash plate 16A is carried out smoothly, so that the operating speed of the pump swash plate 16A for a given gap of the pump swash plate 16A lowers at the beginning of the displacement and so that, when the vehicle stops where a slowing operation of the pump swash plate 16A is performed a positio In the case of a speed increase at the neutral position, the operation of the pump swash plate 16A is carried out at a higher speed, so that at the moment of the stopping of the vehicle the speed of operation of the 16A pump swash plate for a given offset of pump swash plate 16A becomes larger.

  This allows changes in response to the beginning of movement and stopping of movement by actuation of the shift pedal 24. This also helps to prevent a sudden acceleration possible at the beginning of the movement of the vehicle.

  As the mapping data of the first actuating speed setting means 31B, the forward motion mapping data for the shift actuation speed prevailing at the time of a forward movement, and the backward displacement mapping data for a shift speed actuating speed prevailing at the time of backward movement may be provided separately, so that the means 31C The speed change feature has different mapping data to be used based on the information detected from the pedal sensor (forward or reverse motion detection means) 29.

  When the forward travel deceleration spring 32 and the rearward travel deceleration spring 33 perform a return operation to the neutral position (deceleration operation) of the pump swash plate 16A, the inertia existing at the moment of a towing operation, or otherwise, may make it difficult to obtain a slowdown operation to the neutral position of the pump swashplate 16A despite the slowing operation of the shift pedal 24.

  Thus, despite the deceleration actuation of the shift pedal 24 which is performed on the basis of the information detected from the pedal sensor 29 and the information detected from the swash plate sensor 30, when it is detected that the deceleration operation of the pump swash plate 16A by means of the forward-biasing deceleration spring 32 or the rearward-travel deceleration spring 33 is not performed, the pump swash plate controls the actuation of proportional valve 36 for forward movement or proportional valve 37 for backward movement away from the side used to actuate pump swash plate 16A up to the active position present. Thus, the pump cylinder 26 is moved 2891605 21 to act in the direction in which the deceleration operation of the pump swash plate 16A is effected to the neutral position.

  As a result, even though the pump swash plate 16A does not decelerate despite the fact that the speed at which the shift pedal 24 is operated slows due to inertia, for example, during a towing operation, or the like, the deceleration operation of the pump swash plate 16A can be effected by a forced actuation of the pump cylinder 26 via the actuation control of the proportional valve 36 relative to the forward movement or the proportional valve 37 relative to the displacement. rearward by the control means 31A of the pump swash plate.

  FIG. 9A shows the vehicle engine stalling performance for large jobs carrying the continuously variable hydrostatic type shift device 10. This engine stall performance is determined by the torque output of the engine. motor 1, the pressure of the continuously variable hydrostatic shift device 10 and the operating position (swashplate angle) of the pump swash plate 16A.

  The line L shown in FIG. 9A is a line indicating engine stall performance, where the engine rotational speed and the pump swing plate 16A actuation position equilibrate at the moment of load. the hydrostatic-type continuously variable speed change device 10 in which the releasing of the high pressure of the continuously variable hydrostatic type speed changing device 10 releases the pressure due to the current load.

  In Fig. 9A, the rotational speed of the motor is indicated relative to the rotational speed set by 100%, and the operating position of the pump swing plate 16A shown relative to 100% of the maximum acceleration position. (maximum angle of the swashplate).

  The performance of the heavy-duty vehicle carrying the continuously variable hydrostatic speed changeover device 10 with respect to engine stalling will be explained in connection with FIG. 9A. When an actuating load for driving tools other than the current load is applied to the motor 1 while the pump swash plate 16A is held at a certain operating position, as shown by the point a, the speed of the The rotation of the motor 2891605 22 and the actuation position of the pump swash plate 16A can come into the region Za within the line L of engine stall performance.

  In this case, when the actuating load other than the current load, etc., is stable, even if the current load increases, the rotational speed of the motor does not collapse. However, if the actuating load other than the current load, etc., increases, the rotational speed of the motor drops and the motor 1 stops or stalls.

  If the pump swash plate 16A is held at a certain operating position, as indicated at point b, when the rotational speed of the motor and the operating position of the pump swash plate 16A are in the region outside the line L engine performance in terms of stalling, then, in the case where the current load increases, the rotational speed of the engine drops and the motor 1 stops.

  If the pump swashplate 16A is held at a certain operating position, when the rotational speed of the motor and the operating position of the pump swashplate 16A are placed in the region Zc, as shown by the point ç, if the current load increases, the rotational speed of the engine drops until it reaches the level of the line L of engine stall performance. Once the Engine Performance Line L is reached, the engine rotation speed will stabilize.

  The line L of engine stall performance is such that, when the output level of the motor 1 decreases, the actuating position of the pump swash plate 16A relative to a given rotational speed of the engine that we can see Figure 9A becomes smaller.

  Thus, the smaller the output level of the engine 1, the less likely the engine is to be stalled due to an overload at the moment of acceleration when the shift pedal 24 is engaged while moving with a large current load, or when climbing a slope.

  To solve this problem, as shown in FIG. 6, the control device 31 is made to have a pump swash plate automatic control means 31D, which changes the operating position of the pump swash plate 16A to the basis of the engine load.

  As shown in FIGS. 6 and 9B, the pump automatic platen control means 31D has an actuation program which calculates the amount of decrease (motor level lowering amount) from the speed of rotation. rotation set for the rotational speed of the motor based on information detected from the fixed rotation sensor (an example of fixed rotational speed detection means) 52, which has a potentiometer which detects the fixed rotation speed of the 1 from the actuating position of the accelerator lever 51 at the flight deck 8, and based on information detected from the rotation sensor 47, a plurality of mapping data (a example of correlation data) which correlates the rotational speed of the motor with the actuation position of the pump swing plate 16A, the control program which actuates the plateau oscillating pump 16A by controlling the actuation of proportional valve 36 for forward movement or proportional valve 37 for backward movement based on calculation results and program mapping data actuating.

  Each mapping data of the pump swash plate automatic control means 31D is determined on the basis of the engine timing performance line L. The rotational speed of the motor and the operating position of the pump swash plate 16A are correlated so that when the rotational speed of the motor falls in the predetermined region h of rotation of the motor, the lower the speed of rotation, and the further the limit actuating position is close to the neutral position and so that the limit actuating position of the pump swing plate 16A is not fixed to the neutral position (see Fig. 9B).

  To explain in more detail, as shown in FIG. 9B, in a first region h 1 where the magnitude of lowering of the motor level is small among the predetermined regions of rotation of the motor, the rotational speed of the motor and the position of the motor. Actuation of the pump swash plate 16A is correlated so that the change amount of the pump swashplate 16A is large for a given amount of variation in the rotational speed of the motor.

  In the second region h2, where the amount of lowering of the motor level is greater than in the first region h1, the rotation speed 2891605 24 of the motor and the operating position of the pump swash plate 16A are correlated that the amplitude of variation of the pump swashplate 16A is small for a given magnitude of variation of the rotational speed of the engine so as to have a stabilization point p where the speed of rotation of the motor does not fall due to the current charge.

  The rotational speed of the motor and the operating position of the pump swashplate 16A are correlated in the third region h3, where the magnitude of falling of the motor level is greater than in the second region h2, so that the magnitude The variation of the pump swash plate 16A is important for the given amplitude of variation of the rotation speed of the motor.

  The control program of the automatic control means 31D of the pump swash plate sets the operating position of the pump swash plate 16A in correspondence with the magnitude of drop of the motor level that the operating program has calculated under the the limit actuation position of the pump swash plate 16A based on the calculation results and the operation program mapping data, and controls the actuation of the proportional valve 39 for the forward or reverse movement; of the proportional valve 37 relative to the backward movement on the basis of the fixed limit actuation position and the information detected from the swash plate sensor 30, so that the limit actuating position of the pump swash plate 16A coincides with the actual actuating position.

  Thus, with the automatic pump swash plate control means 31D, when the rotational speed of the motor falls in the first region hi due to an increase in the load of the motor, the load control is effected while the driving torque increases while stalling the motor by returning the pump swash plate 16A in the slowing direction significantly, with a reduction in the rotational speed of the motor.

  When the rotational speed of the motor falls in the second region h2 despite this load control, the load control can be implemented to prevent stalling of the motor at the same time that priority is given to increasing the torque of the motor. by driving down the deceleration operation amount of the swash plate 16A and increasing the driving torque at the same time that the driver is allowed to test the load of the motor. If the load on the engine is the current load, the rotational speed of the engine will stop decreasing below the stabilization point p once the speed has reached point p. The difference between Figure 9B and Figure 9C is that the vertical axis of Figure 9C represents the rotational speed of the motor. The "Max" indication refers to the fit of the mapping data for a large load and the "IDL" indicates the adjustment of the mapping data for a light load.

  When the speed of rotation of the motor falls in the third region h3 following a load other than the current load, for example from a lifting action of a tool allowing lifting, it is possible to implement a load control which sets the drive torque while giving priority to stall prevention of the motor, via the return, of a significant amount of the pump swash plate 16A in the slowing direction and by reducing the lowering of the motor rotation speed.

  With this command, a load control that prevents engine stallage due to overloading can be performed during a load operation where a front loader A is connected to the tractor or during a tilling operation where a tillage implement is connected to the tractors, etc., even if the driver performs a change operation without taking into account the actuating load, etc. Thus, an improvement in the system response can be expected.

  In addition, since the limit actuation position of the pump swashplate 16A is never positioned on the neutral point, the pump swashplate 16A does not return to the neutral position as a result of this load control. This avoids the possibility that the pump swash plate 16A will return to the neutral position and that the vehicle, unintentionally starting, will not go backward under the effect of the load control during operation. climbing a slope.

  The controller 31 has a plurality of matching data that correlates the rate of change of the rotational speed of the motor with the operating speed of the pump swashplate 16A. It has a second actuating speed setting means 31E, which includes a control program which sets the target operating speed of the pump swashplate 16A on the basis of these matching data. information detected from a variation rate detection means 53 which detects the rate of change of the rotational speed of the engine.

  Each of the matching data of the second actuating speed setting means 31E correlates the rate of change of the rotational speed of the motor with the operating speed of the pump swashplate 16A so that the higher the the engine rotational speed is large, and the operating speed of the pump swash plate 16A increases.

  The control program of the second means 31E for setting the operating speed sets the operating speed of the pump swashplate 16A which corresponds to the rate of change of the speed of rotation of the motor detected by the detection means 53 rate of change, in respect of the target operating speed of the pump swashplate 16A, based on the stored mapping data and the information detected from the velocity detecting means 53, and the velocity of fixed target actuation is outputted by means 31D of automatic control of the oscillating plate pump.

  The control program of the automatic pump plate control means 31D controls the actuation of the proportional valve 36 relative to a forward movement or the proportional valve 37 relative to a rearward displacement so that the pump swash plate 16A is actuated at the target operating speed which is fixed by the second actuating speed setting means 31E. Thus, good load control taking into account the rate of change of the rotational speed of the motor is possible. Despite variations in the rate of change of the rotational speed of the engine, driving comfort is maintained during a fall or an increase in the rotational speed of the engine. In addition, a deceleration operation of the pump swash plate 16A for lowering the rotational speed of the motor can be performed with a sufficient response capacity, and it is possible to prevent stalling of the motor resulting from the delay of actuation of the swash plate. pump 16A.

  The rate of change detecting means 53 has a rotation sensor 37 and an actuating program relating to the second actuating speed setting means 31E which calculates the rate of change of the speed of rotation of the motor on the motor. the basis of the information detected from the rotation sensor 47.

  The data changing means 31C has a control program that modifies the mapping data that is used by the pump swash plate automatic control means 31D and the second operating speed setting means 31E. The data changing means 31C transforms the mapping data that the pump swash plate automatic control means 31D uses to match data which correlates the rotational speed of the motor with the operating position of the pump. pump swash plate 16A, based on the information detected from the fixed rotation sensor 52, so that the smaller the rotational speed of the motor 1 is set, and the larger the pump swashplate control variable 16A for a given change in the rotational speed of the engine will be large (see Figure 9). It also modifies the mapping data that the second operating speed setting means 31E uses in matching data which correlates the rate of change of the rotational speed of the motor with the speed of actuation of the swash plate. 16A, on the basis of information detected from the fixed rotation sensor 52, so that the smaller the fixed rotational speed of the motor 1, and the greater the amount of control of the pump swash plate 16A for a given change in engine rotational speed will be large (see Figures 9A, 9B, 9C). It also modifies the mapping data that the second actuating speed setting means 31E uses in matching data which correlates the rate of change of the engine rotational speed with the actuation speed of the engine. pump swash plate 16A, based on information detected from the stepped shifter sensor 45, so that the transmission rate of the shifter gear unit 11, or gears, is low, and faster the operation of the pump swash plate 16A occurs and so that the operating speed of the pump swashplate 16A becomes larger for a rate of change of the rotational speed of the motor with lowering of the transmission rate of the gearing device 11 of the stepped type.

  Thus, an appropriate charge command is chosen on the basis of the matching data with respect to the fixed rotational speed of the motor 1. Therefore, regardless of the fixed rotational speed of the motor 1, it is possible to effectively prevent engine stallage due to overload.

  According to the transmission rate of the stepped type gear shifter 11, which is shifted to the low speed side when performing an operation with a larger load, the matching data is set so that the lower the transmission rate, the greater is the operating speed of the pump swashplate 16A for a given rate of change in the rotational speed of the motor. Thus, a deceleration operation of the pump swash plate 16A can be quickly performed in response to a rapid reduction in the rotational speed of the motor during a high load operation.

  As a result, motor stalling can be reliably prevented by overloading.

  While not shown, the manually operated actuating speed setting device (an actuating speed setting means) is provided and having a potentiometer or a switch for setting the desired actuating speed of the actuator. 16A pump swash plate during load control, etc. The automatic control means 31D of the pump swash plate can be installed in such a way that it controls the operation of the proportional valve 36 relative to a forward movement or the proportional valve 37 relating to a rearward displacement so that the pump swash plate 16A is operated at the target operating speed which is set by this operating speed setting device with respect to the operating load which varies depending on the type of tool attached.

  An actuation tool relating to a data change instruction (instruction supply means) which has a potentiometer, a switch, etc., can be provided for the data changing means 31C in the cockpit 8, so as to instruct a change in the mapping data used by the automatic pump swash plate control means 31D or the second actuating speed setting means 31E. This allows the matching data to be changed according to the attached equipment.

  This tractor is equipped with a switching mechanism 54 that switches the swashplate (motor swashplate) 17A of the variable capacity motor 17 between high and low positions.

  The switching mechanism 54 has a hydraulic cylinder 55 which actuates the motor swashplate 17A, a switching valve 56 which controls the flow of hydraulic fluid to this cylinder, an electromagnetic control valve 57 which actuates the switching valve 56 , a high pressure selection valve 58 which allows the supply of hydraulic fluid from the closed circuit 20 of the continuously variable speed changing device 10 of the hydrostatic type to this control valve 57, a switching lever 59 disposed at the position lower left relative to the steering wheel 6, a lever sensor 60 which has a switch which detects the actuating position of this switching lever 59, and a motor swash plate control means 31F that comprises the control device 31 as a control program that performs up-down switching operation for the bone plate motor 17A on the basis of the information detected from this lever sensor 60.

  The cylinder 55 relative to the engine and the variable capacity motor 17 are removably housed inside the second housing portion 4B of the gear case 4.

  When the switching lever 59 is actuated to the low speed position on the basis of information detected from the lever sensor 60, the motor swash plate control means 31F performs a high-low switching control which makes switching the motor swash plate 17A from the high speed position to the reduced speed position, and turning on the corresponding indicator lamp 61. When the shift lever 59 is actuated at the high speed position, it performs a low-lift switching control which switches the motor swash plate 17A from the reduced speed position to the high speed position and turns on the corresponding indicator lamp 62.

  Thus, when the vehicle speed drops substantially due to a load increase, during climbing of a slope or a local operation while the switching lever 59 is placed in the high speed position, the driving force , or driving force, supplied to the right and left front wheels 3 and to the right and left rear wheels 5 may be increased by switching the shift lever 59 to the reduced speed position, from the high speed position, so that the vehicle may continue to climb or continue to perform heavy work.

  The indicator lamps 61 and 62 are arranged in the control panel 63 which is placed under the steering wheel 6.

  The motor swashplate control means 31F stores the present operating position of the pump swashplate 16A in the up / down switching control means based on information detected from the swash plate sensor 30, calculates the desired operating position for slowing down the pump swash plate 16A, and controlling the actuation of the proportional valve 36 relative to the forward movement or the proportional valve 37 relative to the rearward displacement so that the deceleration operation of the pump swash plate 16A is performed at a predetermined operating speed to the calculated slowdown target operating position. The means 31F controls the actuation of the proportional valve 36 or 37 and the control valve 57 such that, after the pump swash plate 16A has reached the slowing target operating position, an accelerated return of the plateau pump oscillator 16A at the stored operating position with the predetermined operating speed and a switching operation of the motor swash plate 17A moving from the high speed position to the reduced speed position at a predetermined speed are executed simultaneously ( see Part A of Figure 10).

  In addition, in the bottom-up switching control, based on information detected from the swash plate sensor 30, the operating position of the pump swash plate 16A is stored, and the position of slugging of the pump swing plate 16A is calculated. Actuation of proportional valve 36 for forward movement or proportional valve 37 for backward movement and actuation of control valve 57 are controlled so that the plateau deceleration operation pump oscillator 16A leading to the target operating position of deceleration calculated at the operating speed and the switching actuation passing from the reduced speed position to the high speed position of the motor swash plate 17A at the operating speed are performed simultaneously.

  After this, the actuation of the proportional valve 36 relative to the forward movement or the proportional valve 37 relative to the rearward movement is controlled so that the pump swash plate 16A returns to the position of actuation stored at the predetermined speed. (See Part B of Figure 10).

  Thus, when switching the motor swash plate 17A to the reduced speed position, from the high speed position, through the execution not only of the switching actuation, but also of the acceleration actuation of the swash plate of At the same time, the variation of capacity of the variable capacitance motor 17 produced by the switching actuation to the reduced speed position of the motor swashplate 17A from the high speed position can be shifted by a change in the variable capacity pump, or variable flow rate, 16 produced by an acceleration actuation of the pump swash plate 16A. In addition, when switching the motor swash plate 17A to a high speed position, from a reduced speed position, through the execution not only of the switching actuation, but also of a deceleration operation of the swash plate of At the same time, the variation of capacity of the variable capacitance motor 17 produced by the switching actuation to shift to the high speed position of the motor swashplate 17A from a reduced speed position can be shifted by the change in capacity of the variable capacity pump 16 produced in connection with the deceleration operation of the pump swash plate 16A. Thus, the shock due to the passage that is produced by a switching actuation of the motor swashplate 17A can be alleviated.

  In addition, although this is not shown, instead of the switching valve 56, a quick-response valve may be used. When the motor swash plate control means 31F performs a switching operation of the motor swashplate 17A, the fast response valve is serviced so that the operating speed of the swash plate of 17A motor can fall to slow down any variation in capacity of the variable capacity motor 17 that is produced during the switching of the motor swashplate 17A, which reduces the shocks of passage resulting from the variation of capacity of the variable capacity motor 17 .

  When a movement is made while the motor swashplate 17A is switched to the high speed position, the motor swash plate control means 31F can perform a switch control passing from top to bottom in connection with a braking action of a braking system, based on information detected from the brake sensor 49, which has the effect of improving the braking operation.

  In addition, the motor swashplate control means 31F can be configured to perform switching control switching from top to bottom when moving while the motor swashplate 17A has switched in the high speed position on the basis of information detected from the pedal sensor 29, and information detected from the swash plate sensor 30, regardless of the deceleration operation of the shift pedal 24, when it is detected that the deceleration operation of the pump swash plate 16A with the deceleration spring 32 relative to the forward movement or the deceleration spring 31 of the rearward movement is not performed, so that the switching command from top to bottom can perform a deceleration operation if the deceleration operation of the pump swash plate 16A is not performed E due to inertia during a towing operation, etc., despite the deceleration operation of the shift pedal 24.

  Further, the motor swashplate control means 31F can be configured to perform the top-down switching command based on information detected from the operation speed detection means 46, when the motor swash plate 17A has switched to the high speed position, and when the operating speed of the shift pedal 34 is higher than a predetermined operating speed, so as to prevent an unexpected start and a sudden acceleration.

  As shown in FIG. 1, the switching lever 59 is installed so that the actuable end is placed in the vicinity of the left part of the steering wheel 6. This allows a switching operation to be carried out, passing from the top to the the bottom of the engine swash plate 17A, without the hand having to lift from the steering wheel 6. In addition, when the front loader A (see Figure 6) is 2891605 33 connected to the tractor, the switching actuation up The bottom of the motor swashplate 17A can be performed without the hand being lifted from the control lever for effecting the operation of the front loader (not shown) disposed on the right side of the steering wheel 6.

  As shown in FIGS. 4 to 6, the control device 31 has an automatic motor swash plate control means 31G and a control program. A motor 31G automatic swash plate control means performs an automatic up-and-down switch, which switches the motor swash plate 17A to the low speed position, from the high speed position, and turns on the corresponding indicator lamp. When it is detected, based on the information detected from the pedal sensor 29, that the operating position of the shift pedal 24 is activated on the predetermined operating position or the operating area. when the rotational speed of the motor has been detected as having fallen to the motor speed of the up-to-down switching in the vicinity of a predetermined maximum torque output rotation frequency, or a speed region of the motor from the bottom-up switching which is fixed for a given actuating position of the shift pedal 24 on the basis of maximum torque output characteristics of the motor 1, and the motor drop-out amount calculated by the operating program 31D of the automatic pump swash plate control means. The pump automatic swash plate control means 31G also performs the automatic up-and-down switching control which switches the motor swash plate 17A to the high speed position, from the reduced speed position, and turns on the corresponding indicator lamp. 62, when it has been detected, on the basis of the falling amplitude of the motor level, that the rotational speed of the motor has reached the switching speed from bottom to top in the vicinity of a rotational speed predetermined setting or the motor speed region for switching from bottom to top, and when the actuation of the shift pedal 24 leading to the actuating position or the previously fixed operating area is detected on the information base detected from the pedal sensor 29.

  In particular, if the actuating position of the pedal 24, in the maximum foot depression position is 100%, is 50% or less, for example, the automatic switching control passing from the top to the Low is achieved when the engine rotational speed drops to 85% of the engine speed. If the operating position of the pedal 24 is 90%, or more, the automatic up / down switching control is performed when the motor rotation speed drops to 70% or less. When the rotational speed of the motor reaches 90% or more, the automatic up / down switching is performed when the operating position of the pedal 24 is performed at 90% or more.

  Thus, a large load state is naturally assumed when the amount of drop of the engine level is important while the shift pedal 24 is operated on a large amplitude.

  However, if a certain amount of engine level drop occurs when the amount measuring the driving operation of the shift pedal 24 is small, a high load state is assumed where a significant drop in speed motor rotation is expected with a significant depression operation of the pedal 24. Therefore, even if the amount of falling of the motor level is small, a switching command passing from top to bottom is performed to ensure a sufficient driving force. Therefore, even if the driver does not perform a shift operation taking into consideration an actuating load, or the like, high load operation, which requires a large motive power, can continue without the engine being driven. down. Just when the driver tends to want to accelerate further while the load is falling and the rotational speed of the motor increases to approximately a predetermined fixed rotational speed, the switching control is passed from bottom to top. and the speed of the vehicle increases. This avoids the disadvantage that a bottom-up switching command is performed resulting in unexpected acceleration despite the fact that the driver reduces the amount of depression exerted on the shift pedal 24 for a deceleration associated with a decrease. of the charge.

  In the switching control from the top to the bottom of the motor swing plate automatic control means 31G, when the switching actuation is effected, the vehicle speed is low due to the displacement load and the shock of the passage is supposed to be small. Therefore, the control for lightening the shock of the passage as in the switching command passing from top to bottom in the motor swash plate control means 31F is not performed. The actuation of the proportional valve 36 relative to the forward movement or proportional valve 37 relative to the rearward displacement is controlled so that the switching operation of the motor swashplate 17A is effected from the position high speed to go to the reduced speed position with the predetermined operating speed. After switching the motor swash plate 17A to the reduced speed position, this state is maintained for a predetermined duration (for example 2 s).

  In addition, for the switching control from the bottom to the top of the motor swing plate automatic control means 31G, the same control action as for the up-and-down switching in the control control means 31F. motor swashplate takes place, and the shock of the passage produced by the switching action passing from bottom to top the motor swashplate 17A is lightened. After switching the motor swash plate 17A to the high speed position, this state is maintained for a predetermined time (for example 2 s).

  It is also possible to configure the motor swash plate automatic control means 31G so that it performs the automatic up / down switching control which causes the motor swashplate 17A to switch from the high speed position to the position reduced speed and turn on the corresponding indicator lamp 61, when the rotational speed of the motor is detected as having fallen to the switching speed from bottom to top in the vicinity of a predetermined maximum torque output rotation speed, or in the motor speed region relative to the switching from low to high, based on the maximum torque output characteristics of the motor 1, and the motor level drop amplitude calculated by the operating program of the motor; means 31D automatic control of pump swash plate and so that is performed an automatic control switching from bottom to top that The motor swashplate 17A is switched from the reduced speed position to the high speed position when the rotational speed of the motor has been detected as being mounted up to the switching speed from bottom to top in the vicinity of the predetermined fixed rotational speed, or in the engine speed region relating to switching from low to high, based on the magnitude of falling of the motor level, and the illumination of the indicator lamp corresponding 62 is performed.

  The controller 31 has a mode switching means 31H acting as a control program which switches the control mode executed on the basis of the operation of the mode setting device 64, which has a normally open switch on its own. display panel 63. When an "ON" signal (i.e. "on") is inputted in connection with the pressure on the mode-setting device 64, the mode-switching means 31H causes the transmission control mode to switch between a manual control mode, a semi-automatic control mode and an automatic control mode, and it lights one of the indicator lamps 65 to 67 corresponding to these respective control modes. In the manual control mode, it performs the speed control using the control actuation of the pump swash plate control means 31A and the control of the switching using the control command of the plateau control means 31F. oscillating motor. In the semiautomatic control mode, it performs the speed control which uses a control actuation of the pump swash plate control means 31A, and a load control using the control actuation of the automatic swash plate control means 31D. of a pump, and a switching control using a control actuation of the motor swash plate control means 31F, so that priority can be given to the load control as opposed to the speed control. In the automatic control mode, the mode switching means 31H performs a speed control which utilizes the control actuation of the pump swash plate control means 31A, and a load control using the medium control actuation. 31D automatic pump swash plate control, and the automatic switching control that uses the motor swing platen auto control medium 31G control actuation, so that the priority is given to the load control as opposed to the speed control, and so that the load control and the automatic switching control are appropriately coordinated.

  Thus, when the manual control mode is chosen, the pump swash plate 16A is actuated on the basis of the operating position of the shift pedal 24, etc., so as to arrive at the position of targeted actuation which corresponds to the position of actuation of the shift pedal 24 with the target operating speed. The motor swashplate 17A will switch between the high and low positions based on the operation of the shift lever 59.

  The pump swash plate 16A is actuated on the basis of the operating position of the shift pedal 24, etc., so as to arrive at the target operating position which corresponds to the operating position of the gearshift pedal 24 with the target operating speed. When a motor speed drop occurs, based on the magnitude of the motor level drop, etc., it is made to arrive at the limit operating position that corresponds to the motor level drop amplitude for the target operating speed, and the motor swash plate 17A switches between the high and low positions based on the operation of the shift lever 59.

  When the automatic control mode is selected, the pump swash plate 16A acts so as to arrive at the target operating position which corresponds to the operating position of the shift pedal 24 for the desired operating speed. . When the engine speed drops, the pump swash plate 16A is actuated to arrive at the limit operating position corresponding to the motor level drop amplitude for the target operating speed, based on the amplitude of motor level drop, etc. The motor swashplate 17A switches between the high and low positions with appropriate timing on the basis of the operating position of the shift pedal 24, or the magnitude of the level drop of the motor, etc. Thus, if the manual control mode is selected, for example, for movement and light load operation, or if the semi-automatic control mode is chosen when climbing a relatively steep slope, and for medium load operation, or if the automatic control mode is selected when climbing a very steep slope or for a heavy load operation, so that movement and operations can be performed without increasing the load for the driver.

  Note that in the automatic control mode load control, the lower limit speed of the motor 1 is set at a lower level than the load control of the semi-automatic control mode, so that the control sensitivity is fixed at a low level which tends to cause a drop in engine speed. Therefore, the automatic switching control that makes the motor swash plate 17A switch to a low speed position can be easily performed.

  Further, when the switching operation to the low speed position of the motor oscillating plate 17A on the basis of the operation of the switching lever 59 is performed in the automatic control mode, since it is impossible to performing the switching operation to the reduced speed position of the motor swash plate 17A by an automatic switching command, the control mode automatically switches from the automatic control mode to the semiautomatic control mode.

  As shown in FIG. 11, the instrument panel 63 has a liquid crystal display device 69 in which the display can be changed between a vehicle speed display mode, a remaining fuel display mode, etc., based on the operation of the display switching switch 68. This liquid crystal display device 69 displays the target operating position 69A or the limit operating position 69B and the current position 69C of the pump swashplate 16A which changes at any time, when the position display mode of the pump swash plate was selected by operating the display switching switch 68. Thus, by selecting the pump swash plate position display mode, it is arranged that the movement of the pump swash plate 16A can be controlled easily.

  It will be noted that part (A) of FIG. 11 shows the situation in which the aiming operating position 69A allowing acceleration for the pump swash plate 16A has been fixed. Part B of Figure 11 shows the situation in which the pump swash plate 16A is actuated toward the target operating position 69A for acceleration. Part C of Figure 11 shows the situation in which the target operating position 69A or the limit operating position 69B associated with a slowing down of the pump swash plate 16A is positioned.

  When a tool, for example a front loader A, is mounted so as to be vertically movable, while a height sensor 70 comprises a potentiometer which detects the height position of the tool, the data changing means 31C changes the mapping data, which correlates the operating position of the shift pedal 24 with the operating position of the pump swashplate 16A which uses the pump swash plate control means 31A, tooling-up mapping data stored in the pump swash plate control means 31A based on the information detected from the height sensor 70, while the tooling is raised up to a position of height higher than a predetermined height (a height position that exceeds the height of the vehicle).

  In comparison with the mapping data which is ordinarily used, the tooling lift mapping data sets the operating position of the pump swashplate 16A for a given operating position of the drive pedal. gearshift 24 on the low-speed side. (See Fig. 7.) Since the pump swash plate control means 31A uses this mapping data, the speed of the vehicle will be limited to the low speed side, and a high speed displacement will be prevented when the tooling has been raised higher than a fixed height.

  As can be seen in FIGS. 4 and 5, the servo control mechanism 25 has a servo valve 27, a regulator valve 28 and a swash plate sensor 30, as well as a temperature sensor 43. oil, which are housed in the housing 71, which is releasably connected by means of bolts through the right-hand side portion of the second housing portion 4B of the gear housing 4 and is embodied as an actuating mechanism 72. This electronically actuated mechanism 72 can be easily changed into a mechanical type mechanism by replacing a block-type mechanical unit 76 incorporating the actuating axis 73 operatively connected to the gearshift pedal 24 by the intermediate of a link mechanism (not shown) of the mechanical type, as shown in FIGS. 12 and 13, and the servo valve 74 which has a coil which controls the flow of hydraulic fluid to the cylinder 26 for pumps disposed in the housing 75 which is bolted to the right-hand side portion of the second housing portion 4B of the gear housing 4.

  In addition, the element bearing the reference numeral 77, which can be seen in FIGS. 4 and 12, is a link arm used in the electronically controlled servocontrol mechanism as a reaction arm placed between the cylinder 26 of the pumps and the swash plate sensor 30 and used, in the mechanical servo control mechanism 78, as the actuation / reaction combination arm placed between the cylinder 26 of the pumps and the actuating pin 73 to actuate the servo valve 74.

  In addition, the elements bearing the reference numerals 78 and 79 which are shown in FIGS. 5 and 13 are connection openings formed in the surface which bears against the second housing portion 4B of the housing 71 allowing the connection to the openings connection 80 and 81 when the electronic type mechanism 72 is connected by screws to the right side portion of the second housing portion 4B.

  As shown in FIGS. 4 and 5, the switching mechanism 54 having the switching valve 56, the control valve 57 and the high pressure selection valve 58, is embodied as a single block constituting the switching mechanism. control 84 because it is housed by the housing 83 releasably connected by bolts to the left-hand side portion of the second housing portion 4B of the gear housing 4. The device can be modified and can pass adjustable specifications of the motor to fixed engine specifications in a relatively simple manner by replacing the actuating mechanism 84 with a plate 85 as shown in FIGS. 12 and 14 by overlapping connection holes 86 to 91 which are formed in the surface with the actuating mechanism 84 of the second housing portion 4B, by replacing the variable capacity motor 17 located in the second housing portion 4B by the motor r with fixed capacity 92 and by removing the cylinder 55 relative to the engine.

  In addition, the elements bearing the reference numerals 93 to 98 shown in FIG. 5 are communication ports formed in the welded surface with the second housing portion 4B of the housing 83, which are connected to each port of FIG. corresponding communication 89 to 91 of the second housing portion 4B when the switching mechanism 54 is connected by bolts to the left side portion of the second housing portion 4B.

  Due to the aforementioned structure, the arrangement can be changed in a simple manner from one arrangement which has an adjustable motor and an electronic-type servo control mechanism (see Fig. 5), a provision having an adjustable motor and a servo control mechanism 78 of the mechanical type (see Fig. 13), an arrangement having a fixed motor specification and an electronic servo control mechanism (see Fig. 4) and a disposition having a fixed motor and a servo control mechanism 78 of the mechanical type (see Figure 15), which brings a reduction in cost, since parts can be used in sharing, and facilitates the management of parts.

  As shown in FIG. 6, the end regions of the operating area of the shift pedal 24 can be set as high speed regions, and a region between the two ends can be fixed. as a low speed region, and the motor swashplate control means 31F can be adapted to control the actuation of the control valve 57 based on information detected from the pedal sensor 29, so that that when the shift pedal 24 is actuated to the low speed region, the engine swash plate 17A switches to a low speed position, and when the shift pedal 24 is operated to the region of high speed, the motor swash plate 17A is placed in a high speed position in order to use the shift pedal 24 also as an actuating element for a two-position high and low switching of the variable capacity motor 17. The end regions of the operating area of the shift pedal 24 can be set as a high speed region and the 31F motor swash plate control means may be adapted to control the actuation of the control valve 57 based on information detected from the pedal sensor 29, so that when the shift pedal 24 is operated to go into the high speed region, the motor swashplate 17A switches to high speed position in order to use the speed change pedal 24 also as an actuating element for a switch from low to high speed. top of variable capacity motor 17.

  Thus, when the shift pedal 24 is also used as an actuating element for switching the variable capacity motor 17, an expansion mechanism (not shown) may be provided to indicate the boundary of the operating area. of the gearshift pedal 24.

  Another embodiment of the invention is described below.

  The same reference numbers are used to designate parts identical to those of the embodiment mentioned above and the descriptions for the identical parts will be omitted.

  Other embodiments (1) The heavy-duty vehicle may be a self-carrying type rice planting machine (ie with a driver's seat), a self-carrying type mowing machine , or a wheel loader.

  (2) The continuously variable speed changing device 10 may be of the belt type, or the like.

  (3) The correlation data may have a plurality of correlation equations that correspond to various conditions and, or may have multipliers corresponding to various conditions.

  (4) A planetary gear transmission may be used in place of the stepped gear shifter 11.

  (5) An electric cylinder, an electric motor or a hydraulic motor, etc., may be used as control means 55.

  (6) The shift control 24 may be a shift lever, or the like.

2891605 43

Claims (12)

  A heavy duty vehicle charge control structure, comprising: fixed rotational speed detecting means (52) for detecting the rotational speed set for the motor (1) of a gross vehicle works; means for detecting the actual rotational speed, which detects the actual rotational speed of the motor; a continuously variable speed changing device (10) which receives power from the heavy duty vehicle engine (1); a shift position detecting means (30) for determining the shifting actuation position of the continuously variable shifting device; an actuating means for shifting the velocities of the continuously variable speed changing device; control means (31) for controlling the operation of the actuating means; characterized in that: the control means (31) calculates the magnitude of lowering the actual rotational speed of the motor relative to the rotational speed set based on the information detected from the rotational speed detecting means. and the actual rotational speed detecting means, the control means sets a limit actuating position for the continuously variable shift device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with continuously variable speed changing device operating positions, the control means controls the actuating means so that the operating position of the continuously variable speed changing device moves to the limit actuation position based on the fixed limit actuation position and information detected by firing the shift position detecting means 2891605 44 and that the controlling means has instruction providing means which provides the instruction to perform a change of the correlation data.   The heavy duty vehicle load control structure according to claim 1, characterized in that the instruction supply means has the fixed rotational speed detecting means, and the control means (31) changes. the correlation data based on information detected from the fixed rotational speed detection means, such that the smaller the engine rotational speed is set, and the greater the amplitude with which the gearshift device continuously variable (10) is actuated is large for a given change in the actual rotational speed of the motor (1).   A load control structure for a heavy duty vehicle, characterized in that it comprises: fixed rotational speed detecting means (52) for detecting the rotational speed set for the engine (1). ) a heavy-duty vehicle; actual rotational speed detecting means, which detects the actual rotational speed of the motor; a continuously variable speed changing device (10) which receives power from the heavy duty vehicle engine (1); shift position detecting means (30) for determining the shifting actuation position of the continuously variable shifter; an actuating means for shifting the velocities of the continuously variable speed changing device; control means (31) for controlling the operation of the actuating means; an operating speed setting means for setting an operating speed at which the continuously variable speed changing device (10) is actuated; wherein the control means (31) calculates the magnitude of lowering the actual rotational speed of the motor relative to the rotational speed set based on the information detected from the fixed rotational speed detection means and of the actual rotational speed detecting means, the control means sets a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the speed of rotation. actual rotation of the motor with operating positions of the continuously variable speed changing device, the control means controls the actuating means so that the operating position of the continuously variable speed changing device moves to the position of limit actuation on the basis of the fixed limit actuation position and information detected from the mean wherein the control means controls the operation of the actuating means so that the continuously variable speed changing device (10) is actuated by the actuating means at the operating speed. fixed by the operating speed setting means.   Load control structure for heavy duty vehicle according to claim 3, characterized in that the operating speed setting means calculates the rate of change of the actual rotational speed of the motor (1) on the based on the information detected from the rotational speed detection means and sets the operating speed so that the higher the calculated rate of change, the higher the operating speed.   The heavy duty vehicle charge control structure according to claim 3 or 4, characterized in that the structure further comprises a stepped gear shifter and a stepped shifting position detecting means for detecting the speed position of the stepped shifter, and that the operating speed setting means controls the actuating means, based on the information detected from the shifting position detecting means, stepped speed, so that the stepped gear shifter's speed position is lower and the higher is the speed at which the continuously variable gear shifter (10) is activated to the limit actuation position.   2891605 46 Load control structure for heavy duty vehicle according to claim 1 or 5, characterized in that the control means (31) never sets the limit actuating position for the continuously variable gear change position ( 10) on the neutral position.   7. A method for controlling the speed of a heavy-duty vehicle, the heavy-duty vehicle having: a fixed rotational speed detecting means for detecting the rotational speed set for the engine of a vehicle for big jobs; means for detecting the actual rotational speed, which detects the actual rotational speed of the motor; a continuously variable speed changing device (10) which receives power from the heavy duty vehicle engine; a shift position detecting means for determining the shift actuation position of the continuously variable shift device; an actuating means for shifting the velocities of the continuously variable speed changing device; control means for controlling the operation of the actuating means, the method comprising the steps of: calculating the amount of lowering of the actual rotational speed of the motor relative to the rotational speed set based on the detected information from the fixed rotational speed detecting means and the actual rotational speed detecting means; setting a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with the operating positions of the changeover device continuously variable speed; controlling the actuating means so that the operating position of the continuously variable speed changing device moves to the limit actuating position on the basis of the fixed limit actuating position and information detected from the shift position detecting means; and change the correlation data.   The method of claim 7, characterized in that: the means for providing an instruction has a fixed rotational speed detecting means, and the method further comprises the step of modifying the correlation data on the base of information detected from the fixed rotational speed detecting means, so that the smaller the fixed rotational speed of the motor and the greater the amount with which the continuously variable speed shifter acts for a change given the actual rotation speed of the motor.   9. A method for controlling the speed of a vehicle intended for heavy work, the vehicle intended for heavy work having: a fixed rotational speed detecting means for detecting the rotational speed set for the engine; a vehicle for heavy work; means for detecting the actual rotational speed, which detects the actual rotational speed of the motor; a continuously variable gearshift device which receives power from the heavy-duty vehicle engine; shift position detecting means for determining the shift actuation position of the continuously variable shift device; an actuating means for shifting the velocities of the continuously variable speed changing device; control means for controlling the operation of the actuating means; an operating speed setting means for setting an operating speed at which the continuously variable speed changing device (10) is actuated, the method being characterized by comprising the steps of: calculating the magnitude of lowering the actual rotational speed of the motor relative to the rotational speed set based on the information detected from the fixed rotational speed detection means and the actual rotational speed detecting means; setting a limit actuating position for the continuously variable speed changing device based on the calculated lowering amount and correlation data which correlates the actual rotational speeds of the motor with the operating positions of the changeover device continuously variable speed; controlling the actuating means so that the operating position of the continuously variable speed changing device moves to the limit actuating position on the basis of the fixed limit actuating position 2891605 and sensing information detected at from the shift position detecting means; and controlling the operation of the actuating means such that the continuously variable speed changing device is actuated by the actuating means at the actuating speed set by the actuating speed setting means.   The method according to claim 9, further comprising: calculating the rate of change of the amount of lowering of the actual rotational speed of the engine based on the information detected from the detection means of the fixed speed of rotation; setting the operating speed at which the continuously variable speed changing device is actuated so that the greater the rate of change, and the greater the speed of operation of the continuously variable speed changing device.   The method of claim 9 or 10, characterized in that the structure further has a stepped shifter and stepped shifting position detecting means for detecting the shifting position of the shifter. stepped speed and in that the method further comprises the operation of controlling the actuating means, on the basis of the information detected from the stepped gear position detecting means, so that the further position of the The speed of the stepped gear shifter is low and the greater the speed at which the continuously variable gear shifter acts toward the limit actuation position.   12. The method of claim 9 or 10, characterized in that the control means never sets the continuously variable speed shift actuation position to the neutral position.